Solid state image pickup device and method of producing solid state image pickup device
Forming a back-illuminated type CMOS image sensor, includes process for formation of a registration mark on the wiring side of a silicon substrate during formation of an active region or a gate electrode. A silicide film using an active region may also be used for the registration mark. Thereafter, the registration mark is read from the back side by use of red light or near infrared rays, and registration of the stepper is accomplished. It is also possible to form a registration mark in a silicon oxide film on the back side (illuminated side) in registry with the registration mark on the wiring side, and to achieve the desired registration by use of the registration mark thus formed.
1. A solid state image pickup device comprising:
a photo-electric conversion device configured to convert a spectrum of incident light into a signal charge, said photo-electric conversion region being in a pixel region of a semiconductor substrate;
a light-shielding film configured to inhibit transmission of said incident light onto said semiconductor substrate, an opening through the light-shielding film being between a micro-lens and said photo-electric conversion device;
wirings in an insulating layer, said semiconductor substrate being between said light-shielding film and said insulating layer;
a metallic alignment mark within said semiconductor substrate at a first surface of the semiconductor substrate, said first surface being between said insulating layer and a light receiving surface of the semiconductor substrate.
2. The solid state image pickup device according to claim 1 , wherein said metallic alignment mark is a silicide.
3. The solid state image pickup device according to claim 1 , wherein said insulating layer touches and said metallic alignment mark.
4. The solid state image pickup device according to claim 1 , wherein said wirings are metallic.
5. The solid state image pickup device according to claim 1 , wherein said insulating layer is silicon oxide.
6. The solid state image pickup device according to claim 1 , wherein said semiconductor substrate has a thickness, said thickness correlating to said spectrum.
7. The solid state image pickup device according to claim 1 , wherein said incident light through said micro-lens is transmissible onto said photo-electric conversion device through said opening.
8. The solid state image pickup device according to claim 1 , further comprising:
a pixel configured to detect a black level, said pixel being in said pixel region.
9. The solid state image pickup device according to claim 8 , wherein said light-shielding film is configured to inhibit said incident light from reaching said pixel.
10. The solid state image pickup device according to claim 1 , further comprising:
a registration mark between said metallic alignment mark and a portion of the light-shielding film.
11. The solid state image pickup device according to claim 10 , further comprising:
an insulator film between said semiconductor substrate and said light-shielding film, said registration mark being within said insulator film.
12. The solid state image pickup device according to claim 11 , wherein said insulator film is silicon oxide.
13. The solid state image pickup device according to claim 11 , wherein said light-shielding film is within a passivation layer.
14. The solid state image pickup device according to claim 13 , wherein said passivation layer is silicon nitride.
15. The solid state image pickup device according to claim 1 , wherein a photo-electric conversion region of the photo-electric conversion device is between a backside layer of the photo-electric conversion device and said first surface, said backside layer having a conductivity type opposite to said photo-electric conversion region.
16. The solid state image pickup device according to claim 15 , wherein said backside layer touches said photo-electric conversion region and said light receiving surface.
17. The solid state image pickup device according to claim 15 , further comprising:
a charge accumulation region of the photo-electric conversion device between said photo-electric conversion region and a photodiode region of the photo-electric conversion device, said photodiode region touching said first surface and said charge accumulation region.
18. The solid state image pickup device according to claim 17 , wherein said charge accumulation region has a conductivity type opposite to said photodiode region, said photodiode region and said backside layer being of a same conductivity type.
19. The solid state image pickup device according to claim 17 , further comprising:
a channel region between said photodiode region and a floating diffusion portion, said first surface touching said floating diffusion portion and said channel region.
20. The solid state image pickup device according to claim 19 , wherein said floating diffusion portion has a conductivity type opposite to said photodiode region.